Better handle agent errors on the coordinator side

Things like the agent not having the log file, or an output. This will allow
the agent to actually retry the relevant thing.

1 files changed, 18 insertions, 13 deletions

diff --git a/guix-build-coordinator/agent-messaging/http/server.scm b/guix-build-coordinator/agent-messaging/http/server.scm
index c9d70d6..a8e0d46 100644
--- a/guix-build-coordinator/agent-messaging/http/server.scm
+++ b/guix-build-coordinator/agent-messaging/http/server.scm
@@ -457,16 +457,21 @@ port. Also, the port used can be changed by passing the --port option.\n"
         "not-found"
         #:code 404))))
 
-  (call-with-error-handling
-   controller-thunk
-   #:on-error 'backtrace
-   #:post-error (lambda args
-                  (match method-and-path-components
-                    ((method path-components ...)
-                     (simple-format
-                      (current-error-port)
-                      "error: when processing: /~A ~A\n"
-                      method (string-join path-components "/"))))
-                  (render-json
-                   `((error . ,(simple-format #f "~A" args)))
-                   #:code 500))))
+  (with-exception-handler
+      (lambda (exn)
+        (match method-and-path-components
+          ((method path-components ...)
+           (simple-format
+            (current-error-port)
+            "error: when processing: /~A ~A\n"
+            method (string-join path-components "/"))))
+        (if (agent-error? exn)
+            (render-json
+             `((error . ,(agent-error-details exn)))
+             #:code 400)
+            (render-json
+             `((error . ,(simple-format #f "~A" exn)))
+             #:code 500)))
+    controller-thunk
+    #:unwind? #t))
+